Function Generator Circuit using ICL8038

Function Generator Circuit using ICL8038

Function Generators are an essential equipment for electronic hobbyist and experimenters to feed input signal with ease other than generating them by their own. FG’s generally differ with their functionality and the cost will be generally high so that many of us cannot afford it. The above circuit will offer you a alternative by helping you to build a Function generator by your own. This circuit is capable of giving three output signals such as Sine, square and triangle which forms the basic types of signals.


Pin Diagram of ICL8038

The ICL8038 is a function generator chip that can generate three basic signals such as Sine, Square and triangle waveforms. The IC has also provided room to adjust the important parameters of a waveform such as Frequency and duty cycle. The frequency of the signal can be modified from 0.001KHz to 300KHz using external resistors and capacitors.


The external resistors and capacitors plays a great role in working of this circuit as it decides the frequency, duty cycle of the waveform produced. The resistors Ra and Rb is known as the timing resistors , where Ra controls the rising portion of the triangle , sine and high state of square wave. Therefore if Ra is equal to Rb then 50% duty cycle is achieved. A 1k Potentiometer RV3 is equal to alter the duty cycle of the obtained waveform. The large resistor on pin 5 helps reducing the sweep variations with duty cycle.

The pins 7 & 8 of the IC is meant for FM Bias and FM sweep input. Here both the pins are shorted together and connected to a variable resistor RV1 100k , altering the resistance value of RV1 will result in change in frequency of the output wave.

The sine wave from the pin 2 will seem distorted and in order to minimize this a variable resistor Rv4 of 100K is connected to pin 12. Varying the resistance using this will reduce the distortion in the output sine wave. The average levels of the sine and triangle wave are one half of the supply voltage but square wave alternates between V+ and ground. Hence a pull up resistor of 15k is used at the output pin 2 to make the square wave switch between V+ and ground.

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Frank Donald

Frank Donald

Junior Network Engineer at Tata Communications
Frank Donald is an Electronics and Communication Engineer who loves building stuff in his free time. Video games, blogging and programming are the things he loves most

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